The North American climate stabilized around 8000 (BCE), or 10,000 years ago. Climatic conditions were similar to modern patterns; however, the receding glacial ice sheets still covered large portions of the land, creating lakes of meltwater.[12][13] Most population groups during the Archaic periods were still highly mobile hunter-gatherers.[14] However, individual groups started to focus on resources available to them locally; thus with the passage of time there is a pattern of increasing regional generalization (i.e.: Paleo-Arctic, Plano and Maritime Archaic traditions).[14]